1. Field of the Invention
This invention relates to earth working machines and, more particularly, to a cutting system for excavating different types of substances, such as, rock or dirt, and which includes a support block configured to receive a rotatable cutting tool, such as a conical bit cutting tool, or a non-rotatable, indexable cutting tool, such as a spade bit cutting tool, depending on the type of material that is being trenched or excavated.
2. Description of Related Art
Many coal mining and/or construction tools generally include a plurality of bits for cutting into either hard material, such as concrete, asphalt, or rock, or into soft material, such as dirt. The bits are held by support blocks which are generally welded to a cutting chain, drum or wheel, and the blocks may be arranged so that alternating bits project from opposite sides of or staggered positions on the wheel, drum or chain.
Additionally, depending upon the material composition, it may be desirable to use a hybrid bit having properties of both the rotating conical bit and the non-rotating spade bit. Conical bits generally have a cylindrical surface and are rotatable within the support block.
The prior art is directed to different designs for the bits and/or support blocks for holding the bits. U.S. Pat. No. 4,915,454 is directed to a cutting apparatus having a fixed holder and an orientable holder. The fixed holder is mounted to a cutting drum and the orientable holder receives a cutting bit, which may be a conical bit or a forward-attack bit.
U.S. Pat. Nos. 3,318,401 and 4,316,636 are directed to construction tools having a block with a non-cylindrical bore adapted to accept a bit or a tool having a shaft with both a mating non-cylindrical portion and a cylindrical shaft portion.
U.S. Pat. No. 5,106,166 is directed to a mining bit holding system, which includes a bit holder that attaches to a rotatable drum of a mining machine. The bit holder includes a base portion and a body portion. The body portion has an aperture for receiving a co-axial sleeve. The sleeve has a bore for rotatably receiving a cutting bit. The sleeve and the bit holder are constructed such that the angular position of the sleeve may be fixed relative to the common axis of the aperture in the sleeve in a plurality of positions, and the sleeve may be rotated with respect to the axis of the aperture of the body portion to another position and then fixed in that position.
U.S. Pat. No. 4,727,664 is directed to an excavating machine having several support blocks, each having a cylindrical bore for receiving the cylindrical shank of a rotatable type bit. The support block is combined with a non-rotatable dirt type excavating tool. The tool has a cylindrical shank at one end made complementary respective to the block bore so that the shank can be telescopingly received in a captured manner within the bore of the support block. A stop means is formed on the block for engaging an abutment means of the tool and prevents axial rotation of the tool when the shank is received within the bore. The tool can be removed from the block, axially rotated into one of a plurality of axial positions respective to the block, and mounted within the bore of the support block.
U.S. Pat. No. 5,007,685 relates to a trenching tool assembly with dual indexing capabilities that includes a block formed with a tool shank bore and a cutter bit having a shank, which is insertable into the tool shank bore. The shank includes a hex portion. An indexing washer has a central opening that is shaped to engage the polygonal section of the cutter bit shank and to prevent relative rotation therebetween. The washer engages the tool block in a number of fixed positions. To change the angle of attachment of the cutter bit, the indexing washer is disengaged from the tool block and cutter bit shank. The indexing washer and cutter bit shank can be indexed as a unit or independently of one another.
U.S. Pat. No. 4,462,638 relates to a mining machine, which has cutting bits with conically-shaped heads and located in sockets of the support holders that have respective wear sleeves located on the shanks of the bits with the bit free to rotate with the sleeve interposed in the socket, thereby preventing wear mount. A retainer is engageable with a receptacle on the sleeve to ensure against undesired ejection of the bit.
U.S. Pat. No. 4,346,934 is directed to a non-rotatable excavating bit that has a forward working portion and a rearward shank portion, which is circular in cross-section and is adapted to fit into a circular bore of a support block. A tang extends from a shoulder and is adapted to fit down over and mate with a surface of the support block so as to hold the bit non-rotatable bit in the support block.
There is a need to provide a support block that can receive either a rotatable cutting bit, such as a conical bit, for cutting into hard surface materials or a non-rotatable cutting tool, such as a spade bit cutting tool, for cutting into soft surface materials.
It is therefore an object of the invention to provide an indexable cutting tool system for use in trenching and/or excavating different types of materials that includes a support block configured to selectively receive and retain either a non-rotatable, indexable cutting tool or a rotatable cutting tool.